1. Field of the Invention
The present invention relates to a conveyor system, more particularly relates to a conveyor system for conveying a wafer or other thin workpiece having a thickness of not more than 100 μm from a carrying location to another location.
2. Description of the Related Art
When conveying a wafer or other thin workpiece from a carrying location to another location, use can be made of a conveyor system as disclosed in for example U.S. Pat. No. 4,566,726, in particular FIG. 2A and FIG. 2B.
The conveyor system disclosed in this is shown in FIGS. 9A and 9B. The conveyor system is a conveyor system for conveying a wafer or other workpiece 100 provided with a plate-shaped member 102 at the center of one surface 102a where a Bernoulli nozzle 104 is formed. This Bernoulli nozzle 104 has a baffle plate 104a at its nozzle part and a pressurized air blowing port 104b formed in a crescent shape. Therefore, the pressurized air from the Bernoulli nozzle 104 is strongly blown out in the direction of a stopper 106 provided at the outer periphery of the plate-shaped member 102 as shown in FIG. 9B. According to this Bernoulli nozzle 104, the suction force based on the Bernoulli principle, that is, the lift, acts on the workpiece 100 and the workpiece 100 is lifted without abutting against the surface 102a of the plate-shaped member 102. However, the Bernoulli nozzle 104 blows the air out strongly in the direction of the stopper 106, so the workpiece 100 lifted by suction by the Bernoulli nozzle 104 moves in the direction of the stopper 106 and the side surface of the workpiece 100 contacts the stopper 106.
The surface 102a of the plate-shaped member 102 is provided with three vacuum chucking nozzles 108,108, and 108 near the outer periphery of the plate-shaped member 102 along the outer periphery. These vacuum chucking nozzles 108,108, and 108, as shown in FIG. 9A, are connected with a vacuum pump or other vacuum generator (not shown) through a tube 112 and conduit 110 formed in the plate-shaped member 102. The front ends of the vacuum chucking nozzles 108,108, and 108, as shown in FIG. 9A, are provided projecting out from the surface 102a of the plate-shaped member 102. Therefore, the workpiece 100 lifted by the Bernoulli nozzle 104 and abutting against the stopper 106 is chucked to the front ends of the vacuum chucking nozzles 108,108, and 108 without abutting against the surface 102a of the plate-shaped member 102.
According to the conveyor system shown in FIGS. 9A and 9B, the workpiece 100 lifted in a noncontact state with the surface 102a of the plate-shaped member 102 by the Bernoulli nozzle 104 is chucked near the periphery to the front ends of the vacuum chucking nozzles 108,108, and 108, so it is possible to convey the workpiece 100 in a substantially noncontact state with the plate-shaped member 102. Further, the workpiece 100 chucked to the front ends of the vacuum chucking nozzles 108,108, and 108 are in a fixed state with the plate-shaped member 102, 50 by swiveling the plate-shaped member 102, it is possible to easily position the work 100. In recent years, however, the wafers used for semiconductor chips have been made thinner. Wafers of thicknesses of less than 100 μm are being provided to the market. If conveying such thin wafers using the conveyor system shown in FIGS. 9A and 98, it is learned that the wafers will easily fracture or other problems will occur during conveyance.